The article describes results of research devoted to Phytomix-40, a mixture of plant adaptogens. It focuses on immunobiological criteria for its formulation, chemical composition and manufacture procedures, biological standartization tests, in vitro and in vivo preclinical studies, clinical trials in patients with non-malignant tumours (benign prostatic hyperplasia), precancer (oral leukoplakia), advanced cancer (malignant gastric cancer), and age-related neurodegenerative disease (parkinsonism). Prospects for the development of other plant preparations for non-toxic prevention and treatment of cancer and prolongation of life span of the affected subjects are discussed.